Author: Bob Rakovic Grade Level: 9 Course: Biology
Purpose of Unit
Evolution (evolve - v.), simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations).
Understanding evolution is critical for understanding biology. As the preeminent scientist Theodosius Dobzhansky stated, “Nothing in biology makes sense except in the light of evolution.” Evolution explains the striking similarities among vastly different forms of life, the changes that occur within populations, and the development of new life forms.
The idea that life began in a primordial “soup” is both intriguing and confounding. In order to bring clarity to the concept the students will engage in an exercise that utilizes a web-based tutorial that follows a logical progression from soup to cells.
Knowing what evolutionary change is and how it played out over geological time, students can now turn to its mechanism. They need to shift from thinking in terms of selection of individuals with a trait to changing proportions of a trait in populations.
Teaching and learning about evolution have practical value that extends beyond understanding our world. The principles of evolution underlie improvements in crops, livestock, and farming methods.
Natural selection accounts for the rise in pesticide resistance among agricultural pests and informs the design of new technologies to protect crops from insects and disease. Species from microbes to mammals adapt to climate change; studying the mechanism and rate of these changes can help conservation experts formulate appropriate measures to protect species facing extinction.
Understanding evolution is also central to the advancement of medicine and the treatment of human illness and disease. Concepts such as adaptation and mutation inform therapies and strategies to combat pathogens, including influenza. Knowing the evolutionary relationships among species allows scientists to choose appropriate organisms for the study of diseases, such as HIV, H1N1 & emerging diseases.
Understanding the concepts of natural and artificial selection has its place in furthering medical research with regard to the development of vaccines, antibiotic resistance and drug development.
Studying evolution is an excellent way for students to learn about the process of scientific inquiry. Evolution offers countless and diverse examples of the ways scientists gather and analyze information, test competing hypotheses, and ultimately come to a consensus about explanations for natural phenomena. The students will become engaged in
Knowing what evolutionary change is and how it played out over geological time, students can now turn to its mechanism. They need to shift from thinking in terms of selection of individuals with a trait to changing proportions of a trait in populations.
Familiarity with artificial selection, coming from studies of pedigrees and their own experiments, can be applied to natural systems, in which selection occurs because of environmental conditions.
Students' understanding of radioactivity makes it possible for them to comprehend isotopic dating techniques used to determine the actual age of fossils and hence to appreciate that sufficient time may have elapsed for successive changes to have accumulated.
Knowledge of DNA contributes to the evidence for life having evolved from common ancestors and provides a plausible mechanism for the origin of new traits.
History should not be overlooked. Learning about Darwin and what led him to the concept of evolution illustrates the interacting roles of evidence and theory in scientific inquiry. Moreover, the concept of evolution provided a framework for organizing new as well as "old" biological knowledge into a coherent picture of life forms.
Finally there is the matter of public response. Opposition has come and continues to come from people whose interpretation of religious writings conflicts with the story of evolution. Schools need not avoid the issue altogether. Even if students eventually choose not to believe the scientific story, they should be well informed about what the story is.
Learning Performances and Standards:
Grade Span Expectations Evolution Grades 9 through 12
By the end of the 12th grade, students should know that
The basic idea of biological evolution is that the earth's present-day species are descended from earlier, distinctly different species. 5F/H1*
Molecular evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from one another. 5F/H2
Natural selection provides the following mechanism for evolution: Some variation in heritable characteristics exists within every species; some of these characteristics give individuals an advantage over others in surviving and reproducing; and the advantaged offspring, in turn, are more likely than others to survive and reproduce. As a result, the proportion of individuals that have advantageous characteristics will increase. 5F/H3*
Heritable characteristics can be observed at molecular and whole-organism levels—in structure, chemistry, or behavior. 5F/H4a
Heritable characteristics influence how likely an organism is to survive and reproduce. 5F/H4b
New heritable characteristics can result from new combinations of existing genes or from mutations of genes in reproductive cells. Changes in other cells of an organism cannot be passed on to the next generation. 5F/H5
Natural selection leads to organisms that are well-suited for survival in particular environments. 5F/H6a
Chance alone can result in the persistence of some heritable characteristics having no survival or reproductive advantage or disadvantage for the organism. 5F/H6b
When an environment, including other organisms that inhabit it changes, the survival value of inherited characteristics may change. 5F/H6c
Modern ideas about evolution and heredity provide a scientific explanation for the history of life on Earth as depicted in the fossil record and in the similarities evident within the diversity of existing organisms. 5F/H7*
Life on earth is thought to have begun as simple, one-celled organisms about four billion years ago. Once cells with nuclei developed about a billion years ago, increasingly complex multi-cellular organisms evolved. 5F/H8
Evolution builds on what already exists, so the more variety there is, the more there can be in the future. But evolution does not necessitate long-term progress in some set direction. Evolutionary change appears to be like the growth of a bush: Some branches survive from the beginning with little or no change; many die out altogether; and others branch repeatedly, sometimes giving rise to more complex organisms. 5F/H9
The continuing operation of natural selection on new characteristics and in diverse and changing environments, over and over again for millions of years, has produced a succession of diverse new species. 5F/H10 (SFAA)
Prerequisite Knowledge:
individuals with certain traits in particular environments are more likely than others to survive and have offspring
whether a characteristic is considered advantageous or disadvantageous depends on the environment (when the environment changes, the advantageous or disadvantageous characteristics can also change)
heritable characteristics can be physical or behavioral
a population is a group of individuals that belong to the same species, live in the same area, and breed with others in the group
a species is a group of organisms that look alike and are capable of producing fertile offspring in nature
biodiversity is the variety of species living within an ecosystem
mutation, crossing over, and independent assortment are the mechanisms by which genetic variation is created at the molecular level
Translating Standards into Learning Goals:
students should be able to make this key association: individuals that have physical or behavioral traits that better suit their environment are more likely to survive and reproduce than those that do not have such traits
students should be able to explain what is meant by “differential reproductive success” between organisms as the difference between how many offspring individuals are able to leave behind.
students should be able to recognize that an individual with higher reproductive success leaves behind more of its traits in the next generation
students should be able to list the following conditions under which NS is made possible: 1) genetic variation of offspring due to sexual reproduction, 2) the environment having a limited supply of resources that cannot possibly sustain all the offspring that are produced by every individual, and 3) differential reproductive success
students should identify NS as the process by which evolution occurs
students should be able to explain why it doesn’t make sense to say “NS acts on populations” but it makes sense to say “NS acts on individuals”
students should be able to explain why it doesn’t make sense to say “an individual has evolved” but it makes sense to say “a population has evolved”
students should be able to explain that mutation, crossing over, and independent assortment are three genetic mechanisms that lead to new gene combination
students should recognize that new gene combination amounts to different traits found among individuals in a population
students should recognize that new traits may be advantageous or disadvantageous depending on the environment they are found in
students should be able to give an example of an environmental condition and traits that would be advantageous and traits that would be disadvantageous in this condition
students should be able to name a trait that would be advantageous in one environment and disadvantageous in another.
students should be able to define divergence as the accumulation of differences between groups
students should be able to define speciation as the formation of new species
students should be able to recognize that increasing divergence leads to speciation
students should be able to recognize that NS brings about divergence
students should recognize that organisms which are geographically isolated are essentially no longer able to reproduce with one another and therefore create viable offspring.
species become extinct when the environment changes and characteristics of a species are not enough to allow them to survive
most species that have lived on Earth have become extinct (i.e. extinction common)
the fossil record is evidence of extinction and speciation over eons of time.
students should be able to explain how humans can genetically engineer organisms for new traits
Potential Student Misconceptions:
an individual can evolve we must warn them that only populations can be said to evolve
Natural Selection is goal-directed, for example: bats developed wings because they “wanted” or “needed” them. BUT we must warn them that need does NOT direct change! Otherwise, how would extinction be so common?
The idea that different species can interbreed resulting in a new or different species.
changes are induced by the environment and that the mutations which arise depend on the selection pressures present, they may use the following reasoning: “because the environment favored such and such trait, mutants arose in the population that had such and such trait”
Lamarckian notion of inheritance of acquired traits, i.e. the “use and disuse” notion, they may reason like so: “because snakes didn’t use their legs much and they did use their tongues more, over time they lost their legs and their tongues became longer”
Lesson 9 Applications for the Study of Evolution, Today, and for the Future
Lesson 10 Summative Assessment
Assessment Plan Describe how you will assess your students' understanding of the unit's learning goals throughout the unit. These assessments should include formative assessments, e.g. questions that you ask that probe probable misconceptions, embedded assessments, e.g. activity artifacts, and summative assessments, e.g. tests and quizzes. Note: You are encouraged to use the assessment developed in class in this section.
Rationale ** VERY IMPORTANT focus on the following questions:
Making Evolution meaningful for students
The students will be asked to activate their background knowledge and apply it to the concepts within the topic of evolution i.e.how dog breeding directly relates to the concept of artificial selection
Class discussions will focus on individual concepts within the framework of evolution, while allowing students to interject their own experiences and explore how those experiences relate to a given concept i.e. proposing the question: How will you choose your mate; will it be based on physical characteristics or behavioral characteristics?
Students will engage in informal debate with regard to public reaction to the Theory of Evolution over time; thereby being given an opportunity to examine their own thoughts on the topic.
The use of scientific inquiry
The students will engage in an exercise that simulates Darwinian theory the outcome of which will vary by group. The outcomes will help students understand how natural selection tends to create a population more adapted for its environment
Students will become involved in exercises that exemplify both natural selection and selective breeding whereby the outcomes of the exercises vary from group to group, emulating the behavior of nature.
What are the ways in which you assessed student learning?
How did you take account of students' prior experiences and knowledge?
How will you sequence lessons so that they support the understanding of the learning outcomes?
How will you help students make sense of the materials?
Please make use of class readings and discussions in writing your rationale. The rationale is important because it serves as evidence that you are thinking about the unit like a teacher, i.e. going beyond "writing plans" to thinking about how you are going to engage your students with a topic in a way that builds over two or three weeks.
Author: Bob Rakovic
Grade Level: 9
Course: Biology
Purpose of Unit
Evolution (evolve - v.), simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations).
Learning Performances and Standards:
By the end of the 12th grade, students should know that
Prerequisite Knowledge:
Translating Standards into Learning Goals:
Potential Student Misconceptions:
Concepts Addressed in the Unit
Lesson Sequence:
Assessment Plan
Describe how you will assess your students' understanding of the unit's learning goals throughout the unit. These assessments should include formative assessments, e.g. questions that you ask that probe probable misconceptions, embedded assessments, e.g. activity artifacts, and summative assessments, e.g. tests and quizzes. Note: You are encouraged to use the assessment developed in class in this section.
Rationale **
VERY IMPORTANT focus on the following questions:
Making Evolution meaningful for students
The use of scientific inquiry
What are the ways in which you assessed student learning?
How did you take account of students' prior experiences and knowledge?
How will you sequence lessons so that they support the understanding of the learning outcomes?
How will you help students make sense of the materials?
Please make use of class readings and discussions in writing your rationale. The rationale is important because it serves as evidence that you are thinking about the unit like a teacher, i.e. going beyond "writing plans" to thinking about how you are going to engage your students with a topic in a way that builds over two or three weeks.